Chemistry

Faculty Research Summaries | Chairman's Introduction

Laurie J. Butler

Our research investigates the fundamental inter- and intramolecular forces that drive the course of chemical reactions. To experimentally probe the detailed molecular dynamics, both nuclear and electronic, during a chemical reaction we use a combination of molecular beam reactive scattering and laser spectroscopic techniques. Traditionally, predicting rate constants and microscopic dynamics has relied on statistical transition state theories or, in smaller systems, quantum scattering calculations on a single adiabatic potential energy surface that provides the barriers to each reaction. However, a reaction evolves on a single potential energy surface only if the Born Oppenheimer separation of nuclear and electronic motion is valid. Much of our recent work investigates classes of important chemical reactions where the breakdown of the Born-Oppenheimer approximation (the inability of the electronic wavefunction to readjust rapidly enough during the nuclear dynamics) near the transition state alters the dynamics and markedly reduces the reaction rate. The studies test the predictions of emerging quantum theories on nonadiabatic reaction dynamics in small systems and develop an intuitive framework for understanding chemical reaction dynamics in more complex organic and inorganic reactions not yet accessible to precise quantum calculations.

Aaron Dinner

My research group develops and applies theoretical methods for relating cellular behavior to molecular properties. We are particularly interested in how proteins regulate access to genes in the context of the development of the immune system. Understanding how such complex behavior arises from physical and chemical features is a problem in fundamental statistical mechanics, but its solution has direct implications for treating autoimmune pathologies and improving gene therapy and vaccination strategies.

Greg Engel

In recent years, electronic structure calculations have located numerous photochemical reactions in the condensed phase that are predicted to proceed through conical intersections; while some kinetic data exists to bolster theses claims, direct evidence for the presence of conical intersections in the condensed phase is scarce.  Our research focuses on leveraging precise theoretical predictions of the conical intersections structures to predict, identify, and characterize these structures with the ultimate goal of rationally controlling photoreactivity.  We intend to employ laser spectroscopy to watch the reactions, then to invoke theoretical modeling to understand the data and to locate new substrates.  As we move into the spectroscopy of branching reactions, we intend to manipulate macromolecular chaperones to attempt to steer and control the photochemistry.

Karl F. Freed

Our research include the statistical mechanics of polymers in the liquid phase, protein dynamics aggregation, and folding , equilibrium aggregation phenomena, and molecular electronic structure.

We have developed a theory for the statistical thermodynamics of polymers in the liquid state. Our analytical theory is the first and only one to describe the influence of monomer molecular structure on the thermodynamic properties of polymer mixtures. Several applications explain small angle neutron scattering and thermodynamic experiments for polymer mixtures. Our theoretical predictions of a strong pressure dependence to the small angle neutron scattering intensities has been verified. Likewise, we have predicted the possibility that certain block copolymers will form mesoscopically ordered self-assembled structures in the liquid phase upon heating,a bold prediction subsequently verified experimentally. Recent extensions of the theory consider random copolymers, the influence of short chain branching, monomer structure and chain semiflexibility on miscibilities of polymers in the liquid phase, as well as the phase behavior of liquid crystalline systems and the glass transition in polymer systems. The work on the glass transition is providing the first theoretical understanding for the molecular basis oof glass fragiliity. Other theoretical work on polymers describes the common behavior exhibited by reversible equilibrium aggregating systems, including synthetic polymers and the proteins actin and tubulin. We have devised a density functional theory of interfaces in polymer systems to describe interfaces between phase separated polymers and surface segregation profiles of polymers near an impenetrable, patterned surface. 

Philippe Guyot-Sionnest

Quantum Confined Semiconductors. Delocalized electronic wavefunctions are readily achievable in semiconductor quantum dots, such as semiconductor nanocrystal colloids. This leads to extraordinary optical properties, which may lead to applications ranging from full-color displays, to photo-electrochemical cells. We synthesize semiconductor nanocrystals, and control their sizes and their surfaces. Microscopy and nonlinear spectroscopy are used to study the basic aspects of electron dynamics and interaction in strongly confined structures. We currently focus on the doping of nanocrystals and the very unusual infrared response, e.g. electrochromic, as well as the potentially novel electrical transport properties in films made of these artificial atoms.

Molecular Electronics. Organic materials will be at the basis of increasingly many devices, however, electronic conduction in organic molecules, though fascinating, is poorly understood, and so is the mechanisms for molecular ordering of SAMs. This drives the second topic of research. Using low-impedance and low-temperature STM, imaging and transport studies of individual or monolayers of organic molecules are performed. The goal of this research is to gain an understanding of conduction in organic molecules which should uncover novel concepts. We are particularly interested in electronic nonlinearities relying on donor-acceptor or electron-vibration coupling.

Robert Haselkorn

We study the molecular genetics of nitrogen fixation and photosynthesis in cyanobacteria and purple bacteria. We also study genes encoding the enzyme acetyl-CoA carboxylase in plants, parasites and mammals.

The cyanobacterium Anabaena grows in filaments of 100 cells or more. When starved for nitrogen, specialized cells called heterocysts differentiate from the photosynthetic vegetative cells at regular intervals along each filament. Heterocysts are anaerobic factories for nitrogen fixation; in them, the nitrogenase enzyme complex is synthesized and the components of the oxygen-evolving photosystem II are turned off. More than 1000 genes are believed to be differentially expressed during the (irreversible) development of a heterocyst from a vegetative cell. We have cloned and sequenced genes for nitrogen fixation (nif) and others encoding RuBP carboxylase, glutamine synthetase, the D1, CP-47 and water-oxidizing proteins of photosystem II, all the components of phycobilisome rods, and the sigma and core sub-units of RNA polymerase. Mutants unable to fix nitrogen aerobically have been isolated. Among these are some that have altered heterocyst morphology or an altered pattern. Four of these have been studied in detail, using a complementation system to isolate the wild-type gene defective in the mutants. One mutant fails to deposit the necessary glycolipid layer that forms part of the heterocyst envelope. A second mutant fails to make any heterocysts at all. A third makes them only at the ends of filaments. A fourth makes them too late and too frequently! In these cases, the sequences of the complementing genes are highly informative, corresponding to proteins that participate in environment-sensing regulatory cascades. The relationships among these regulatory proteins are being worked out by using the Green Fluorescent Protein from the jellyfish as a cell-specific reporter of gene expression and by controlling expression of the genes with a Cu++-responsive promoter.

Fatty acid synthesis, in plants as well as in cyanobacteria, begins with the reaction catalyzed by acetyl-CoA carboxylase (ACC). ACC in bacteria, including cyanobacteria, is comprised of four subunits: biotin carboxyl carrier protein (BCCP), biotin carboxylase (BC), and two subunits of carboxyltransferase. In chicken, rat, yeast and plants all of these domains reside in a single polypeptide. We have cloned and sequenced genes encoding BC and BCCP from two cyanobacteria and used this information to design probes for the cloning of ACC cDNA from wheat. We have a complete cDNA for the wheat cytoplasmic enzyme and have expressed it in yeast. It turns out that wheat chloroplasts also have an ACC and this one is the real target of the grass-specific herbicides. The chloroplast ACC has been expressed in yeast also, as a chimera with the N-terminal half coming from the cytoplasmic enzyme. This system was used to identify the amino acid residue that is responsible for sensitivity or resistance to the herbicides.

Parasites such as malaria and Toxoplasma contain a primitive chloroplast called the apicoplast. We discovered that the apicoplast contains an ACC that is similar to the chloroplast enzyme of grasses and we have shown that it is the target of the same herbicides that kill grasses. One of our herbicides inhibits the growth of Toxoplasma in human cells in culture and also inhibits the multiplication of Plasmodium yoelli in the mouse. We intend to use the yeast gene-replacement system to screen for new inhibitors of these parasites.

Humans also have two forms of ACC. One, expressed in the cytoplasm of liver and fat cells, is essential for fatty acid synthesis. The other form is expressed in muscle cells and is transported into mitochondria, where it plays a role in the regulation of fatty acid oxidation. Mice without this second form eat a lot and do not gain weight. We are cloning and expressing the human ACCs in yeast and using those yeast strains to screen for inhibitors of ACC2 that do not affect ACC1. These inhibitors will be good candidates for drugs to treat obesity.

ACC also provides an entry into cancer research. The human protein BRCA1 is involved in breast cancer. Recently it has been shown by others to form tight complexes with ACC. Since we are already cloning the human ACC gene, we can look at the ACC domains involved in that interaction and determine which ACC activities are present in the complex.

Chuan He

Much of our research resides at the interface of chemistry and biology. The first area concerns the functional study of alkylation DNA repair proteins. The goal is to uncover novel DNA repair functions mediated by metal-containing proteins and understand damage-searching and repair mechanisms. We also study several metal responsive transcription factors. These transcription factors sense and regulate the intracellular concentration of free metal ions through metal-mediated regulation of gene transcription. We hope to reveal the molecular details of the regulation through biochemical and macromolecular structural studies. We also design and construct biosensors that can sense various metal ions and organic groups by using sensory proteins. The last component of our research centers on catalysis with silver and gold complexes. Several novel reactions catalyzed by high valent silver species have been discovered. We also developed gold-catalyzed aromatic C-H functionalization reactions.

Gregory L. Hillhouse

Much of my group´s research efforts revolves around the study of the transition-metal-mediated reactions of small, energy-rich molecules of fundamental significance in inorganic, bioinorganic, and organometallic chemistry. Specific projects include:

Preparation and Study of Metal Complexes of Nitroxyl (NH=0). The nitrosonium cation (NO+), the nitroside anion (NO­), as well as the conjugate acid of NO­, nitroxyl (NH=O), are thought to be responsible for certain aspects of the rich biological chemistry of nitric oxide (NO). Moreover, NH=O is a common intermediate in Fe-catalyzed enzymatic process important in the nitrogen cycle, (i.e., reduction of nitrite to ammonia and oxidation of ammonia and hydroxylamine). In our studies of the coordination chemistry of NH=O we have reported the preparation of a nitroxyl complex of Re by oxidation of ligated hydroxylamine, and are now extending this chemistry to other NH2OH systems.Since the early metals are oxophilic, it is unlikely that useful catalytic chemistry will be uncovered here, so we are now expanding our research to include late-metal organometallics in which the M-O bonds, once formed, will not be so strong that they can't be easily broken. Our recent discovery that nitrosonium triflate can effect NO+ insertion into metal-hydride bonds provides a general preparative route to M-NH=O complexes, a finding that should greatly facilitate our studies of the reaction chemistry of NH=O.

Atom and Group Transfer Reactions. Our group has a longstanding interest in reactions mediated by transition metals in which an oxygen atom or nitrene (NR) fragment is transferred to an organic molecule. Our recent work in this area has centered on lateseries metals, particularly nickel. We have found that 3- coordinate Ni complexes containing Ni=L multiple bonds (L = CR2, NR, PR) exhibit unique group-transfer reactivity, for example to olefins, and will continue to feature these and related reactions in our future research efforts. Illustrated below is the conversion of a Ni(I) amide to a Ni(II)+ cation by oxidation; deprotonation yields the first imido complex of a d8 metal (structure is shown in the figure).

Michael D. Hopkins

We are interested in inorganic and organometallic complexes and materials that possess interesting electronic, optical, magnetic, and photophysical properties. Central to our research is the use of high-resolution and time-resolved spectroscopic methods to probe the structures, bonding, and dynamics of the ground states and electronic excited states of molecules. This knowledge enables us to rationally design new complexes and materials with specific and enhanced properties.

One of our goals is to prepare and understand transition-metal analogues of conjugated organic polymers. These hybrid materials are interesting because the metal centers enhance the optical and redox properties of the polymers and provide sites for locally controlling them.
A second subject of study is the development of self-assembling periodic overlayers for patterning surfaces. We have discovered a broad class of supramolecular materials based on high-valent metal-alkylidyne building blocks that form weak dative bonds with a variety of neutral bridging ligands. The resulting 1-D and 2-D materials assemble further via noncovalent (CH/π) interactions, resulting in materials with controlled interpolymer geometries. The materials are strongly luminescent, providing a signaling mechanism for reporting on interactions between the molecular grid and its environment.

A third area of research centers on understanding the nature of metal–ligand multiple bonds. Complexes containing these linkages are important catalysts in synthetic, biological, and industrial chemistry.

Rustem Ismagilov

Our research goal is to understand chemical and biological complexity, both top down at the level of systems and bottom up at the level of molecular components. Using chemistry, biological systems respond and adapt to their environments, perform fascinating functions, and even think. We aim to know how networks of biochemical reactions can give rise to the amazing complexity seen in biological systems. In addition, we aim to use this knowledge to build networks of chemical reactions that can reproduce the functions of biological systems.

To achieve this goal, we utilize a multidisciplinary approach. We combine concepts drawn from chemistry, physics, biology, and engineering with microfluidic technologies developed in the lab. In addition to helping us understand complexity, this approach advances the understanding of specific systems, including Drosophila development and blood coagulation. This approach also provides microfluidic tools that advance areas that can benefit from miniaturization, such as membrane protein crystallization and microscale organic reactions (see Publications).

Our top-down investigations are aimed at analyzing complex networks as a whole, which provides a ‘systems’ view of a network and understanding of its overall function. We develop and utilize microfluidic technologies to control and analyze complex networks in both space and time, and to characterize their dynamics. We currently focus on the spatiotemporal dynamics of the robusteness of Drosophila embryonic development and the complex network of blood clotting (hemostasis).

Our bottom-up investigations are aimed at characterizing the molecular components of these networks, which is crucial to the development of medical treatments. We develop and utilize microfluidic technologies to perform functional and structural studies of the biomolecules that compose these networks. For example, we use tiny droplets, femtoliters to nanoliters in volume, to enable microfluidic crystallization of membrane proteins and microgram organic reactions.

Richard F. Jordan

Research in the Jordan group is focused on synthetic and mechanistic organometallic chemistry. The central theme of this work is the interplay between the structures and reactivity of organometallic compounds, especially in systems that are relevant to catalysis. We design reactive organometallic complexes for use as practical catalysts and synthetic reagents, and as probes of fundamental mechanistic issues in catalysis. We use a wide range of synthetic and spectroscopic methods for the manipulation and characterization of reactive materials, most notably anaerobic synthesis techniques, NMR spectroscopy, molecular modeling and X-ray crystallography. Our current efforts are focused on four major topics: catalytic olefin polymerization, stereoselective catalysis, the design of super-electrophilic main group complexes, and the catalytic chemistry of metal carborane complexes.

Catalysts derived from Cp2ZrX2 and other "metallocene" complexes exhibit high activity for polymerization of simple non-functionalized olefins. Metallocene systems are "single-site" catalysts and produce polyolefins with narrow molecular weight and composition distributions. We have shown that the active species in Cp2ZrX2-based catalysts are Cp2ZrR+ cations which are generated from Cp2ZrX2 precursors by alkylation and R-/X- abstraction reactions. We have studied the chemistry of cationic metal alkyls to develop a detailed understanding of the structural and electronic features that are necessary for olefin polymerization activity by metallocenes. We are now exploiting these principles to design new catalysts based on both early and late transition metals and a variety of non-Cp ligands. We are particularly interested in the design of catalysts that will polymerize functionalized olefins such as vinyl chloride or vinyl acetate by insertion mechanisms, in order to prepare new polymers whose properties are superior to those of polymers produced by radical polymerization.

We are also investigating fundamental issues in olefin polymerization. For example, we have designed model d0 metal olefin complexes in which the metal-olefin bonding is enhanced by chelation. Structural and spectroscopic studies of these systems are providing new insights to how d0 metals activate olefins for insertion and polymerization.

We have used insights gained from our studies of cationic metallocene complexes to develop many new classes of reactive metal alkyls. For example, by utilizing carborane ligands in place of Cp- ligands, we have constructed neutral (C2B9H11)( C5R5) M(R) complexes which have the same structures, electron count, and frontier orbital properties as Cp2Zr(R)+ cations. The carborane systems exhibit unique behavior in catalysis, e.g. "self correcting" behavior in which a catalyst "error" that would normally lead to side products triggers a cascade of reactions that modify the catalyst structure and enhance selectivity. More recently we have prepared novel low-coordinate cationic main group alkyls, e.g. {RC(NR')2}Al(R)+ which are of interest as super electrophilic Lewis acids.

Stephen Kent

The Kent research group is devoted to inventing and using new chemistries to reveal how proteins work in nature. To that end, we develop novel methods for the total synthesis of proteins that enable us to apply advanced physical methods in unprecedented ways to understand the chemical basis of protein function. Our goal is to then demonstrate that knowledge by the design and construction of protein molecules with novel properties.

The total synthesis of natural products is arguably the most important intellectual endeavor in the area of synthetic organic chemistry - it drives methodology forward and generates useful compounds in the process. While landmark small molecule syntheses receive a great deal of attention (and rightly so), it should be recognized that the robust synthesis of large proteins has also been a major goal of organic chemistry since the days of Emil Fischer. Our laboratory invented the chemical ligation methods that now enable the routine total chemical synthesis of protein molecules.

Sergey Kozmin

Chemical synthesis plays an increasingly significant role in the advancement of life sciences. Our research program aims to advance this important paradigm. The main emphasis is on invention of new catalytic reactions, practical assembly of complex bioactive natural products, and efficient generation of highly diverse chemical libraries. The parallel objective is to bring together organic synthesis, cell biology and biochemistry in order to enable the development of an arsenal of new small-molecule agents for basic and translational biomedical research.

Ka Yee C. Lee

A wide variety of diseases are results of deficient or abnormal protein-lipid interactions. The elucidation of the interactions between specific proteins and lipids, and the ability to examine and manipulate biomembranes that mimic real life systems hold the key to a better understanding of these diseases. Our research interests lie in the interdisciplinary area which can be termed as "interfacial medicine". Using two-dimensional monolayers, either at the air-water interface or transferred onto solid substrates, and supported bilayers as model systems, along with various microscopy and scattering techniques, we plan to carry out fundamental studies on the interactions between lipids and proteins to gain insights into the biophysical aspects of these diseases.

Donald H. Levy

My research involves laser spectroscopy in supersonic molecular beams. A supersonic expansion cools the vibrations and rotations of a molecule without condensing the molecule out of the gas phase. This greatly simplifies the spectrum of the molecule and allows us to probe the structure and dynamics of large molecules whose spectra would be hopelessly complicated in a normal environment.

One class of problems in which I am interested is the spectroscopy of weakly bound complexes. High resolution electronic spectroscopy is used to determine the structure of these complexes, and this, in turn, provides information about the weak intermolecular forces that hold the complexes together. These complexes also provide the opportunity to do state-to-state photochemistry in a well controlled environment. Using tunable lasers, energy can be injected into a particular vibrational mode, and the migration of this energy from the initially excited mode can be followed.

A second class of problems involves the gas phase spectroscopy of large molecules such as amino acids and peptides that are not ordinarily observed in the gas phase. Such molecules have negligible vapor pressure at room temperature and, if heated, decompose before they sublime. We use laser desorption to introduce them into a molecular beam, and then study their properties spectroscopically. These molecules are naturally occurring spectroscopic probes of biologically interesting systems, but it is difficult to study their intrinsic properties in solution where they naturally occur. The increased spectral resolution available in a cold molecular beam allows us to resolve spectroscopic features due to different conformers and to study the properties of individual conformers.

I am also interested in studying electron transfer and energy transfer in bichromophoric organic molecules. We have measured rates for these processes down to the time resolution of our nsec. lasers, and we will extend these measurements to shorter times using fsec lasers. Bichromophoric molecules have two aromatic chromophores covalently bound to and separated by an inert spacer such as a methylene chain. By varying the spacer and the chromophores, it is possible to tune the interaction between the chromophores in a well controlled way.

Finally, I am interested in studying the laser desorption process. When a solid composed of large, fragile molecules is exposed to pulsed laser radiation, it is often possible to vaporize intact molecules as large as small proteins with no damage to the molecule. This is a striking and unintuitive phenomenon, and I am interested in understanding the mechanism by which it occurs. Using a new instrument that has recently been built, we are able to measure the kinetic energy, internal state, and angular distributions of molecules that have been laser desorbed.

David Mazziotti

Advancement in reduced-density-matrix theory is fostering the development of a new paradigm in theoretical chemistry that promises to promote unprecedented growth in our ability to explore computationally a myriad of chemical questions from structure to reactivity. The immediate impact of my research has been the development of new electronic structure methods with improved accuracy and efficiency for small-to-medium-sized atoms and molecules - both ground and excited-state properties. These methods will assist chemists in investigating experimental properties such as molecular geometries, bond stretching, bond polarity, electron density, dissociation, and excitation energies with reliable, consistent accuracy. The new methodology is not limited to electronic structure but rather is also appropriate for other aspects of chemistry including the prediction of vibrational and rotational molecular properties.

Milan Mrksich

The Mrksich Group has a broad interest in areas that intersect chemistry, biology and materials. A common thread through several of the our programs is the interface between a material and a biological environment. We make use of self-assembled monolayers to design and synthesize surfaces having well-defined structures and properties. The programs are largely problem-driven and address both fundamental and applied questions. Two of these programs are highlighted below.

Cell Adhesion and Migration. The majority of mammalian cells are adherent and must attach to an extracellular matrix in order to survive, proliferate and carry out important metabolic activities. These activities are, in large part, controlled by the ligand-receptor interactions between the cell and the matrix. Our program develops surface chemistries to access substrates that mimic the natural protein matrix, and therefore that provide model systems for understanding the mechanisms by which cell-matrix interactions operate.

Electroactive Substrates. Interfaces between materials and biological fluids are prevalent, including substrates used in tissue culture, biochip microarays used in drug discovery and microfluidic devices used in biochemical assays. The development of interfaces that not only present ligands for selective interaction with proteins, but that can manipulate the activities of the immobilized ligands in real-time would provide new opportunities in basic and applied research. We have a program to develop electroactive interfaces that switch the immobilized ligands on and off in response to applied potentials. This work is based on a physical-organic approach to designing ligands that incorporate redox-active groups to manipulate the ligand activities.

James R. Norris, Jr.

The research of the group involves studies of natural and artificial photosynthesis. The goal of the research is a more complete understanding of the beginning of the process of natural photosynthesis such that artificial photosynthesis can be a reality. The mechanism and structural requirements of photosynthesis are explored via a series of photosynthetic proteins altered by sitedirected mutagenesis and by model compounds. Additional research interests include:

Joseph A. Piccirilli

Our group is broadly interested in the chemistry and biochemistry of nucleic acids with particular emphasis on RNA and RNA catalysis. The laboratory integrates areas of organic chemistry, physical chemistry, enzymology and molecular biology to gain a fundamental understanding of nucleic acid structure and mechanisms of RNA catalysis. Using the principles and techniques of organic chemistry and molecular biology, we manipulate the structure of RNA molecules at precise locations in ways that are designed to answer very specific questions about biological function.

Viresh H. Rawal

Chemistry is, ultimately, about chemical reactions-developing them, understanding them, and using them to make interesting, useful molecules. Much of the activity in my research group is aimed at discovering new ways to make complex molecules, including the design of unique strategies to certain families of natural products and the development of broadly effective methods for chemical synthesis.

The targets for our synthesis studies are selected for their intricate structures as well as their potent biological activities. We strive to devise routes that are concise, stereocontrolled, and high-yielding, and proceed through strategies that examine interesting aspects of structure and reactivity. Among the targets that we have successfully synthesized are: 5-oxo-silphiperfol-6-ene, (+)-tabersonine, geissoschizal, elisapterosin B, and strychnine. The targets that we are currently pursuing include the clinically important anticancer agent vinblastine, and the potent antiviral and anticancer agent mycalamide A.

Norbert F. Scherer

The common theme of our research is the direct time-domain study of chemical reactions and photophysical processes in condensed media, biomacromolecules and optically important materials. Our interest is in the elucidation of the microscopic dynamics of the system and the role of the bath on all relevant timescales for the chemical, biological and physical processes through development and application of new spectroscopic and simulation methods. Two current programs are highlighted below.

Femtosecond Reactivity and Solvent Response to Chemical Reaction. Solvent plays an important role in chemical reactions by serving at various times as an energy source, a frictional drag, or a bath to stabilize reaction products. Our studies of reactive processes initiated and probed with femtosecond pulses ranging from the far-IR to the near UV reveal oscillations resulting from impulsively excited nuclear wavepacket motion of vibrations coupled to the reactive coordinate, as well as rapid product formation and relaxation. Systems under investigation include organic, inorganic and metallo-protein charge–transfer molecules, excitation localization in polymers and photo-induced "switches" in proteins. A complementary objective is the detection of the solvent´s response to chemical reactions by way of new multiple-pulse Raman methods and terahertz (FIR) spectroscopies. We have developed 2-D polarization response spectroscopy (2-D PORS) to examine the instantaneous spectrum of solvent motions coupled to reaction at various times after the reaction commences.

Coherence Spectroscopy of Complex Systems. Photon echo techniques are being developed and employed to uncover the interactions between a chromophore and the surrounding solvent, the evolution of coherence in chemical reactions, and the fluctuations occurring within proteins. Application of these techniques to the photosynthetic reaction center of cyano-bacteria is revealing details of the protein´s role in the fast energy and electron transfer processes. A second direction of inquiry combines experimental characterization of the complete complex electric field of pulses in linear and nonlinear spectroscopies with correlation function finite difference time domain (CF-FDTD) simulations. These comparisons, initially developed to address ultrafast mid-IR measurements of water, are providing new insight into the proper description of matter–radiation interaction with coherent and incoherent light. The approach facilitates the study of dephasing onto the timescale of a few cycles of the pulse electric field

Steven J. Sibener

Our research interests currently center on using experimental and theoretical techniques to address fundamental questions in the fields of surface chemistry and catalysis, surface physics, and materials research, and, most recently, thin film polymer dynamics and AFM imaging studies of bacterial cell wall structure. In particular, we are using a variety of molecular beam, laser spectroscopic, and scanning probe microscopy techniques, as well as computational tools such as molecular dynamics, to examine issues central to our understanding of surface chemical dynamics. Illustrative topics include: surface chemical kinetics and reaction dynamics, surface photochemistry, metallic oxidation and corrosion, atomically structured thin films, supersonic beam growth of electronic materials, and, most recently, thin film polymer dynamics. These studies are being conducted under ultra-high vacuum conditions, with recent extension to electrochemical environments. They are motivated by a desire to understand and control surface chemical processes at the molecular level, and by the increasing need to understand the physical properties of low-dimensional interfacial systems.

Dmitri Talapin

Our research focuses on chemistry, physics and material science of inorganic nanostructures. By combining expertise in colloidal synthesis, self-assembly and characterization of nanomaterial properties our group creates novel materials for electronic, photovoltaic, thermoelectric and catalytic applications.

Colloidal synthesis of inorganic nanostructures is developing into a new branch of synthetic chemistry. Starting with preparations of simple objects like spherical nanoparticles, the field is now moving toward more and more sophisticated structures where composition, size, shape and connectivity of multiple parts of a multicomponent structure can be tailored in an independent and predictable manner.

Hisashi Yamamoto

My research group is concerned with Lewis and Brønsted acid catalysis. Our work is characterized by the designing of new synthetic catalyst for tailoring the selectivity and relativity and the use of these substrates in both fundamental studies of organic synthesis.

An excellent candidate as a proton substitute in man-made organic reactions is a Lewis acid. The goal of our research is to engineer an artificial proton of a special shape, which could be utilized as an effective tool for chemical reactions, by harnessing the high reactivity of the metal atom towards a variety of functional groups. Such a concept was initially researched by examining the influence of a specially designed organometallic reagent on a various organic reactions. The successful discrimination observed lead to examine the more intricate question of enantioface differentiation, which was first reported from our laboratory and now widely expanded in the world. During the last decade the uninterrupted expansion of Lewis and Brønsted acid catalysis research has continued in organic synthesis. New catalysis research in our laboratory is targeting more versatile, more selective, and more reactive catalysts, targeting environmentally benign system.

Jun Yin

The research of our lab is at the interface of chemistry, biology and medicine. We are working toward:

To achieve these goals, our lab develops and employs a wide variety of biochemical and biophysical methods, including DNA library construction, phage display, enzyme directed evolution, organic synthesis, cell culturing, chemical genetics, high throughput proteomics, enzyme kinetics and molecular imaging.

Luping Yu

My research is focused on the interfacial area between organic chemistry and materials science. This area has rich opportunities for organic chemists both in fundamental science and practical technologies. There are five current projects in the group.These projects are polymerization methodology, molecular electronics, photorefractive and electro-optic polymers, functional polymers containing metal complexes, and supramolecular assembly of nanostructured materials.